In the manufacture of optoelectronic components or devices, in particular organic optoelectronic devices such as, for example, organic light emitting diodes (OLEDs), OLED displays or organic solar cells or photovoltaic cells (organic photovoltaic (OPV) cells), it is desirable firstly to hermetically seal the devices against air (in particular against moisture (water) and oxygen contained in the air), and secondly to protect them against mechanical damage (e.g. scratches), in order to avoid failure of the device.
The sealing of the device or the protection of the device against mechanical damage can be achieved by means of an encapsulation of the device.
For the encapsulation and mechanical packaging of organic optoelectronic components (e.g. OLEDs) on glass substrates, the encapsulation by means of glass cavities is known. In this technique, a glass cover is adhesively bonded onto the component (device) using a specific adhesive. This technique can largely prevent the ingress of harmful influences. However, in the region of the adhesive bond, water and oxygen can still diffuse into the component. As a countermeasure in this respect, water- and oxygen-binding materials (so-called getters) can be introduced (e.g. adhesively bonded) into the cavity. By way of example, non-transparent getters composed of zeolite can be adhesively bonded into the cavity. The getters can absorb the water and oxygen before the organic materials are damaged. The glass cover can simultaneously afford sufficient mechanical protection.
FIG. 1 shows an arrangement 100′ including an organic light emitting diode (OLED) 100 and conventional encapsulation by means of a glass cavity in accordance with one example.
The OLED 100 includes a substrate glass 101. A functional layer stack (OLED stack) 102 is arranged on the substrate glass 101. The functional layer stack 102 may include one or a plurality of organic functional layers (i.e. layers that serve for generating light). Furthermore, electrodes can be provided for making electrical contact with the organic functional layers. An encapsulation glass 103 (also designated as cover glass or cap glass) is adhesively bonded onto the substrate 101 and encloses the functional layer stack 102 in such a way that a cavity (a hollow space) 104 is formed. A getter 105 is introduced into the cavity 104 (by adhesive bonding onto the inner side of the encapsulation glass 103 above the functional layer stack 102), which getter is intended to absorb water and/or oxygen penetrating through the adhesive bond between substrate 101 and encapsulation glass 103 and in this way is intended to prevent the water and/or oxygen from damaging the layer(s) of the functional layer stack 102. The OLED 100 is embodied as a bottom emitter, i.e. the light emission takes place through the transparent substrate glass 101. The getter 105 may consist of a non-transparent material (e.g. zeolite).
FIG. 2 shows an arrangement 200′ including an organic light emitting diode (OLED) 100 with conventional encapsulation by means of a glass cavity in accordance with another example.
The arrangement 200′ differs from the arrangement 100′ shown in FIG. 1 in that, instead of one individual large getter 105 (as in FIG. 1), two smaller getters 205 are introduced into the cavity 104. The two getters 205 are adhesively bonded on the inner side of the encapsulation glass 103 in edge regions of the encapsulation glass 103. The OLED 100 can be embodied as a transparent OLED (light emission both downward through the substrate glass 101 and upward through the encapsulation glass 103), or as a top emitter (light emission only upward through the encapsulation glass 103). As an alternative to the arrangement shown in FIG. 2 including two getters 205 arranged in edge regions, one or a plurality of perforated getters can also be introduced or provided in the cavity 104.
The method of cavity encapsulation is very cost-intensive overall. Moreover, the use of (rigid) glass covers or glass cavities is not suitable for the manufacture of flexible (i.e. pliable) components (e.g. flexible OLEDs).